There is probably some sort of date-difference function that you can use to calculate dates.
Another way might be to generate a timstamp for 12am of the current day, so you'd get the current year, month, day and teh string would be "20050620000000". There are 6 zeros on the end of that because you want from midnight. Then do a query like this.
"select * from sometable where timestamped > mytimestring"
That should work. maybe. I know it works in MySQL. I'm not familiar with mSQL though, might have different functions and syntax.